The present invention relates to an inertial separator, and to an oil module, a cylinder head cover, and an intake module in which such an inertial separator is integrated.
An inertial separator for mechanically separating liquids and/or solid particles from a gas stream is known from German Patent Application No. DE 200 04 131. This inertial separator comprises two sheet metal shells mutually connected to a hollow body. Profiles are arranged parallel to one another at regular intervals in the sheet metal shells. The profiles in the first sheet metal shell are opened in the direction of the gas flow, and the profiles in the second sheet metal shell are opened in the direction opposing the gas flow. The profiles are formed by the incorporation of slots in the sheet metal shells with subsequent bending of the slotted regions. The bent regions interlock with one another, thereby reversing the gas stream twice before it passes through the inertial separator. This double reversal of the gas stream causes droplets or solid particles entrained in the gas stream to be propelled by centrifugal force against the profile. A liquid film thus forms on the interior of the profile which slowly drains down into a collecting channel.
Similar inertial separators are also known from Wimboeck, U.S. Pat. No. 5,342,422 (=EP 615 098).
Bending of the slotted regions creates transition zones in which there is insufficient reversal of the gas stream between the profiles. In this design, impurities may be impelled through the inertial separator, thereby impairing its efficiency.
It is an object of the invention to provide an improved inertial separator.
Another object of the invention is to provide an inertial separator which reliably removes impurities from a gas stream.
These and other objects are achieved in accordance with the present invention by providing an inertial separator for separating particles or droplets from a gas stream, the separator comprising a gas inlet, a gas outlet; a plurality of separation lamellae arranged between the inlet and the outlet, the separation lamellae each having an arcuately-shaped design with a concave side and a convex side; at least two first separation lamellae being linearly arranged next to one another separated by an interval A with their convex sides facing the inlet, and at least two second separation lamellae being arranged offset from the linearly arranged first separation lamellae with the concave sides of the second separation lamellae arranged opposite the concave sides of the first separation lamellae, and a drainage slope for the separated impurities provided on the separation lamellae.
The inertial separator according to the invention is advantageously suited for removing impurities such as dust or liquid droplets from a gas stream. To this end, the inertial separator comprises a housing with an inlet through which the gas to be purified enters the inertial separator and an outlet through which the purified gas exits. The inlet may have various cross sections, such as circular or rectangular shapes, for example. The outlet likewise may also have any desired cross section. However, the cross sections of the inlet and of the outlet need not correspond to one another. For example, the inlet may be designed as a circular bore and the outlet as a rectangular aperture. In other variants, the inlet and outlet may correspond to one another in area as well as in cross-sectional shape.
Arcuately-shaped separation lamellae are arranged in the housing between the inlet and the outlet. The separation lamellae have a concave side and a convex side as a result of their arcuately-shaped design. The separation lamellae may also have, for example, an undulating shape with a plurality of inflection points. The separation lamellae may be made of synthetic resin material, for example, to reduce the weight of the component, although of course other materials such as metals may be used to produce the separation lamellae. The choice of material for the separation lamellae depends on the required material properties or environmental conditions. Metallic materials are better suited for high temperatures, whereas synthetic resin materials may be preferred under low thermal loads for cost reasons.
The inertial separator has at least two first separation lamellae which are linearly arranged next to one another and separated by an interval. This interval creates a gap between the first separation lamellae, which are situated with their convex sides facing the inlet. Second separation lamellae, likewise linearly arranged, are provided offset from the linearly arranged first separation lamellae. These second separation lamellae are arranged with their concave sides opposite the concave sides of the first separation lamellae.
A drainage slope is provided on the separation lamellae on which the separated impurities can drain off. A separate drainage slope may be provided on each individual separation lamella. Alternatively, a single drainage slope may join all first separation lamellae or all second separation lamellae, or all first and second separation lamellae combined. The drainage slope preferably extends at an angle between 0xc2x0 and 90xc2x0 relative to the inlet. The separated impurities slide downward via the drainage slope, and thus can no longer be carried through the inertial separator. In addition, the drainage slope prevents a leakage air stream from flowing past the separation lamellae.
Separated impurities such as oil may be conducted from the drainage slope back to the untreated oil side, thereby being returned to the oil circulation system. Other impurities such as dust, if not recirculated, are conveyed to a waste receptacle, for example, which is emptied as needed.
To facilitate the sliding of impurities down the drainage slope, the drainage slope may be provided with a surface structure which agglomerates the impurities and thus accelerates their sliding motion. The surface structure may be provided with indentations or channels which are arranged, for example, parallel or at any desired angle to the direction of the incoming gas flow.
The gas flowing through the inlet is deflected and guided by the convex sides of the separation lamellae into the gap between the first separation lamellae. The gas stream is xe2x80x9cbundledxe2x80x9d by the gap and impacts against the center of the concave side of the second separation lamellae. Impingement of the gas stream on the second separation lamellae causes the impurities to be propelled against the separation lamellae, where drop-like impurities adhere and flow off. Dust-like impurities likewise fall downward.
The gas stream is divided by the concave side and its flow is reversed. The reversal of the gas stream occurs in the region of the greatest acceleration, with the impurities being pressed against the separation lamellae by centrifugal force. After this first reversal the gas stream is turned back to the first separation lamellae, where it impacts against the concave sides of the first row of separation lamellae. The remaining impurities in the gas stream are separated on these first separation lamellae. The gas stream is again reversed by the concave sides of the first separation lamellae, and thus xe2x80x9cbundled,xe2x80x9d the purified gas can then exit from the inertial separator through the outlet.
Depending on the purity of gas required after the impurities are separated, a plurality of successive rows of separation lamellae may be provided. The purer that the gas exiting the outlet is required to be, the greater the number of successive rows of separation lamellae that are provided.
Furthermore, the degree of purity of the gas may also be regulated by the size of the gap between the separation lamellae. The higher the required purity of the gas, the narrower the gap that is chosen. In this regard it is important that the pressure drop caused by the inertial separator increases as the gap size decreases. Therefore, the gap size should be chosen to be as large as possible in order to optimize the ratio of the separation rate to the pressure drop.
The separation lamellae are designed with a wall thickness as small as possible which at the same time assures sufficient stability of the separation lamellae. To this end, the wall thickness of the separation lamellae may be 0.1 to 10 mm. The stability of the separation lamellae must be adjusted to the operating conditions or the loads, for example, the incoming gas flow rate, which act on the separation lamellae. The wall thickness of the separation lamellae depends on the material used. Smaller wall thicknesses may be used with higher-strength materials than with lesser-strength materials. The size and weight of the inertial separator may be reduced by use of correspondingly thin separation lamellae.
In accordance with one advantageous embodiment of the invention, the drainage slope is provided on the second separation lamellae. The drainage slope may be designed, for example, as a single piece with the separation lamellae. Alternatively, the drainage slope may be designed as a separate component and be connected to the second row of separation lamellae. In such case, the drainage slope may be connected to the second separation lamellae in a detachable manner, such as with screws, or in an undetachable manner, such as with adhesive. As a result of this design, the separation lamellae have a shape that is simple and economical to produce.
According to one embodiment of the invention, the drainage slope terminates at the first separation lamellae, with a small space existing between the drainage slope and the first separation lamellae through which the separated impurities can drain away. By providing the drainage slope underneath the first separation lamellae, the separated impurities from the first and second separation lamellae may be removed via the same drainage slope. Furthermore, this drainage slope prevents a portion of the gas stream from bypassing the separation lamellae and escaping unpurified through the outlet.
It is advantageous to provide a drip spout on the drainage slope to allow better drainage of impurities into a collection chamber. This drip spout has a downwardly tapering design which facilitates detachment of individual drops at the lower end of the drip spout.
In a further embodiment of the invention, the separation lamellae are arranged at an angle between 90xc2x0 and 180xc2x0 relative to the inlet. With this arrangement, the inflowing gas first impinges on the first separation lamellae and is caused to flow along the lamellae, thereby separating initial impurities. As a result of this arrangement, the gas stream is also xe2x80x9cgentlyxe2x80x9d reversed, thereby preventing extreme turbulence.
It is advantageous to design the separation lamellae for optimum flow in their lateral end regions along the vertical edge which form the termination of the arcuate shape. This prevents the gas from separating from the separation lamellae, and minimizes the pressure drop caused by the separation lamellae. The flow-optimized edge or end regions may be designed as curves or points, for example. When the edge regions are designed as points, the wall thickness of the separation lamellae constantly tapers until no more material is present. Thus, there is no longer a surface at the edge regions to which the impurities may adhere.
In particular designs of the invention, the separation lamellae are constructed as circular segments, especially corresponding to one-quarter to three-quarters of a circle. These circular segments are simple to produce, and also have a continuous arcuate shape without inflection points which reduces the pressure drop in the inertial separator. The first separation lamellae may be arranged at any desired distance from the second separation lamellae, with the first and second separation lamellae also partially overlapping or interlocking with one another. The closer the arrangement of the separation lamellae to one another, the higher the separation rate of impurities.
In accordance with another embodiment of the invention, a closeable liquid drain is mounted in the housing underneath the separation lamellae. This liquid drain enables liquid separated from the gas stream to be returned to a liquid container or to be removed from the system for disposal.
A valve may be disposed on this liquid drain which is capable of being opened as needed. The valve may be opened automatically by a control or regulator, or manually by service personnel. It is advantageous to situate the liquid drain at the lowest point in a collection chamber for separated impurities. Collection of the impurities via the liquid drain allows the collection chamber to be emptied in a most efficient manner. If only dry particles are separated from the gas stream, these can naturally be removed via the liquid drain, with the liquid drain then acting as a dust discharge.
An oil module for an internal combustion engine has an untreated oil side with an untreated oil inlet and a treated oil side with a treated oil outlet. An oil filter element is arranged between the untreated oil inlet and the treated oil outlet which seals off the untreated oil side from the treated oil side and filters impurities from the oil. This oil module has an inlet aperture for crankcase gas, with the crankcase gas being conducted through an inertial separator as described above and de-oiled. The de-oiled gas exits the oil module through a gas outlet. The separated oil is conveyed to the untreated oil side and thus returned to the oil circulation system.
A cylinder head cover for covering a cylinder head of an internal combustion engine has a gas inlet connection and a gas outlet connection. An inertial separator as described above is arranged between the gas inlet connection and the gas outlet connection. Arranging the inertial separator on the cylinder head cover allows installation spaces, which otherwise would remain unused for design reasons, to be used to separate impurities from a gas. Thus, contaminated gas streams present in a region near the engine may be purified over the shortest distance and returned to circulation. The purification of crankcase gas represents an advantageous use of the inertial separator integrated into the cylinder head cover.
In a further embodiment, at least one cyclone separator is connected downstream of the inertial separator for further cleaning gas which has been pre-cleaned by the inertial separator. The combination of both separation devices facilitates the optimal removal of impurities from the gas.
An intake module for an internal combustion engine has an air inlet and an air outlet, with the air inlet connected so as to communicate with the internal combustion engine. An inertial separator of the type described above is arranged between the air inlet and the internal combustion engine. Various components such as an air filter, an air flow sensor, flaps or valves may also be installed. The inertial separator purifies the air entering the intake module by removing impurities such as dust or water droplets. This inertial separator may be used instead of or in addition to an air filter. When the inertial separator is combined with an air filter, the air is crudely pre-cleaned by the inertial separator, resulting in only a slight pressure drop. In addition, the service life of the filter element is increased, since coarse dirt particles no longer clog the filter.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.